Modern Rodinal Substitutes Part II

Apologies for having to start a new thread but I can't read or even access the first to reply to posts.

So with a bit of telepathy

Originally Posted by Kirk Keyes

Well, there's a problem there, as it's really hard to measure pH accurately when it gets much above 12.5 or so. You have to start getting special electrodes and the like.

But for MSDS work, it doesn't have to be too precise.
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Kirk

A point that's being missed is that A&O give a figure of 2.7% Potassium Hydroxide not 3% in older Agfa MSDS.

The pH is around 14 sure, but the actual requirement is the pH of the working dilute solution rather than the concentrate which is given elsewhere as pH 11.55, which I commented on in the first post of the thread.

Way back Ron (PE) mentioned adjustments to Rodinal before bottling, the question we need to ask is are they adjusting on the basis of the concentrate, or also doing some tests on a dilute sample, as this will be a far more accurate indicator.

Can someone please post a link to this continuation on the original post.

I think HC-110 is rather good as a developer and has good shelf life. I think that some of the higher dilutions of HC-110 have not been fully exploited and may prove to approach Rodinal. I also believe that a Metol based Rodinal, if stable, would be superior to Rodinal.

It's the simplicity of Rodinal combined with the quality of the negatives produced that lead people like Patrick in search of similar developers using different developing agents.

But in a 100+ years it's been copied by many other companies, including Ilford & Kodak but no-one has yet come up with a simple alternative using other developing agents, that keeps well as a single solution concentrate.

This is why Rodinal is so remarkable.

Ian

If I may be allowed to brag a little, PC-TEA is no slouch in that regard. I have not, for some reason, ever made a direct comparison with anything but Acutol, and that was a few years ago.

If I may be allowed to brag a little, PC-TEA is no slouch in that regard. I have not, for some reason, ever made a direct comparison with anything but Acutol, and that was a few years ago.

Originally Posted by Photo Engineer

Ian;

I think HC-110 is rather good as a developer and has good shelf life. I think that some of the higher dilutions of HC-110 have not been fully exploited and may prove to approach Rodinal. I also believe that a Metol based Rodinal, if stable, would be superior to Rodinal.

PE

I rather suspect it's swings and roundabouts once these developers are used highly dilute. I know from experience that Ilford PQ Universal and particularly May & Baker (Champion) Suprol give fairly similar results to Rodinal, but with slight speed loss like HC110 or Ilfotec HC.

My own practical experience is that a Pyrocatechin based developer like Pyrocat (any of Sandy King's flavours) or Meritol (PPD/Pyrocatechin) gives the best balance of qualities for my own work. In fact HC1100 was at one point a a Phenidone (or derivative)/Pyrocatechin developer, which is not a co-incidence. But both Kodak & Ilford had to devise exotic cocktails to gain the stability and and exceptional shelf lfe of the super-concentrates etc.

Back in the mid 80's I tested all these developers along with FX-1 & 2 and a few other and non came close to Rodinal's exceptional qualities. The major difference was loss of film speed. Since then Sandy King came up with Pyrocat, which is the first & only developer that I've found to be better than Rodinal.

You can titrate it with a standard acid. You can make a standard acid by titrating that with a standardized base. Or, you can use potassium acid phthalate (KHP, or potassium hudrogen phthalate) which is a common standard acid and titrate the KOH solution directly with the KHP solid. Use phenolphthalein as the indicator.

That's what all the hip lab cats do, man.

For some odd reason, you made me think of the person who, upon being exposed to a treatise by Thomas Acquinas on "The Divine Simplicity" said "If that's His simplicity, I can't imagine what His complexity would be like."

I would rather spend my time finding out how far I can deviate from "perfection" and still have the essence of Rodinal. I think the essence of Rodinal is a solution of Potassium paraminophenolate with a preservative which might be an ascorbate or a sulfite. It should be easy to prepare it from easily obtainable ingredients.

The ascorbate would contribute to the potency of the developer as it is a developing agent itself. It would decay with time as it also acts as an antioxidant. It would also be affected by the high pH of the KpAP salt and the excess hydroxide present.

For some odd reason, you made me think of the person who, upon being exposed to a treatise by Thomas Acquinas on "The Divine Simplicity" said "If that's His simplicity, I can't imagine what His complexity would be like."

I agree with the comment on Acquinas, but how hard is a titration? After learning to use the balance, titration is usually the first thing they teach you in chemistry class.

You could probably use USP ascorbic acid to titrate against if you really wanted to give it a try...

Last edited by Kirk Keyes; 09-08-2009 at 04:50 PM. Click to view previous post history.

I agree with the comment on Acquinas, but how hard is a titration? After learning to use the balance, titration is usually the first thing they teach you in chemistry class.

You could probably use USP ascorbic acid to titrate against if you really wanted to give it a try...

It wasn't the difficulty of the process that stimulated my wit, it was the fact that it seemed that you expected every APUGer to have the chemicals and to be able and willing to go through that for a Rodinal fix which might or might not be better than store-bought. Seemed more complex than it is, and I'd have to wait a week for delivery of the test gear.

I'll have to see what indicators my hot tub test kit has. I have USP ascorbic acid.

I think HC-110 is rather good as a developer and has good shelf life. I think that some of the higher dilutions of HC-110 have not been fully exploited and may prove to approach Rodinal. I also believe that a Metol based Rodinal, if stable, would be superior to Rodinal.

PE

Some years ago, I used HC-110 a lot, even for developing paper. For film, I usually added a modicum of ascorbate. For paper, I added some carbonate and some sulfite, IIRC. It was always reliable and quick to prepair, which was a virtue at the time. I was working for NASA, principal oboist for both Peninsule and Norfolk Symphonies, and photographing guest artists at dress rehearsals, providing them with prints the next day. Did I mention having six kids?

I have a portion of a bottle a couple of years old, looks and works like new.